Dart Requires Chilkat v11.5.0+

Create JWS Using Private Key on a Smart Card

See more JSON Web Signatures (JWS) Examples

Creates and validates a JSON Web Signature (JWS) using the private key associated with a certificate on a smart card. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This requires the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  // Load the certificate from a smart card.
  final cert = CkCert();

  // Set the smarcard PIN prior to loading
  cert.smartCardPin = '123456';

  // Detect the connected smartcard or USB security token and load the default certificate.
  try {
    cert.loadFromSmartcard('');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Note: Chilkat provides many different ways to load a certificate from a smartcard or USB token,
  // such as selecting a certificate if the card contains multiple certificates with private keys,
  // or working with lower-level PKCS11 or ScMinidriver API's (both of which Chilkat provides).

  // Create the JWS Protected Header
  final jwsProtHdr = CkJsonObject();

  if (cert.isEcdsa()) {
    jwsProtHdr.appendString('alg', 'ES256');
  } else {
    jwsProtHdr.appendString('alg', 'RS256');
  }

  final jws = CkJws();

  // Set the protected header:
  var signatureIndex = 0;
  jws.setProtectedHeader(signatureIndex, jwsProtHdr);

  // Provide the private key via the certificate.
  // This requires Chilkat v11.5.0 or greater.
  jws.setSigningCert(signatureIndex, cert);

  // Set the payload.
  final bIncludeBom = false;
  final payloadStr = 'In our village, folks say God crumbles up the old moon into stars.';
  jws.setPayload(payloadStr, 'utf-8', bIncludeBom);

  // Create the JWS
  // By default, the compact serialization is used.
  final String jwsCompact;
  try {
    jwsCompact = jws.createJws();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('JWS: $jwsCompact');

  // sample output:
  // JWS: eyJhbGciOiJQUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.TRWhwRo5dMv9-8OzrInfJTwmUGYgjLfHk8lqF072ND-FmLWEBnUTOpY8oJXp8FdWw2SalbdOeNlrtlJjwk4XK8Ql2iJ_2qMCtxsvLPhKBOqFoAF4aBvTOEDVJDxf0DaBSiydEEtfTVV2iwBcjWabu5J2XieR5y7QZQtuHsn7T3qKBvCcCejN3Y2oqAT3qMHvu1fTms1r_91wBn_K7Wjd9UkZ1n02qQcUHJznR_OF2BgN7_KWIDAF9ZS9keoju2NPpPelO4yxa2XUPnehY3G7dHKoCxUEQR4d2Xc5voqDASTVCDqQS4PVOZdvT3Ein6-SanAlCwbWBbkvT8g6-5PImQ

  // Now load the JWS, validate, and recover the original text.
  final jws2 = CkJws();

  // Load the JWS.
  jws2.loadJws(jwsCompact);

  final pubKey = CkPublicKey();
  cert.getPublicKey(pubKey);

  // Set the public key used for validation.
  signatureIndex = 0;
  jws2.setPublicKey(signatureIndex, pubKey);

  // Validate the 1st (and only) signature at index 0..
  final v = jws2.validate(signatureIndex);
  if (v < 0) {
    // Perhaps Chilkat was not unlocked or the trial expired..
    print('Method call failed for some other reason.');
    print(jws2.lastErrorText);
    return;
  }

  if (v == 0) {
    print('Invalid signature.  The key was incorrect, the JWS was invalid, or both.');
    return;
  }

  // If we get here, the signature was validated..
  print('Signature validated.');

  // Recover the original content:
  print(jws2.getPayload('utf-8'));

  // Examine the protected header:

  final joseHeader = CkJsonObject();
  try {
    jws2.getProtectedH(signatureIndex, joseHeader);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  joseHeader.emitCompact = false;

  print('Protected (JOSE) header:');
  print(joseHeader.emit());

  // Output:

  // 	Signature validated.
  // 	In our village, folks say God crumbles up the old moon into stars.
  // 	Protected (JOSE) header:
  // 	{ 
  // 	  "alg": "RS256"
  // 	}
}